Tension control for winding machines



y 30, 1950 1. s. ROBERTS 2 509,250

TENSION CONTROL FOR WINDING MACHINES Filed Dec. 19, 1944 INV TOR. f /M 3% Patented May 30, 1 950 UNITED STATES PATENT OFFICE TENSION CONTROL FOR WINDING MACHINES Ingham S. Roberts, Ridley Park, Pa., assignor to American Viscose Corporation, Wilmington, Del., a corporation of Delaware Application December 19, 1944, Serial No. 568,866

20 Claims. 1

This invention relates to an improved system for controlling the operation of a winding machine which is receiving yarn or other material from a source of supply delivering the strand or yarn at approximately constant speed.

It is an object of the present invention to provide for stepless variation in the take up or winding speed; to provide an arrangement for accurately, reliably, and safely controlling the winding speed by means which are sensitive to the tension in the strand being wound regardless of the strength of the strand; and to provide for adjustably predetermining what variation, if any, of tension shall be imparted to the strand as the package being wound increases in diameter. Further objects and advantages of the invention will be apparent from the drawing and description thereof.

In the drawing, which is illustrative of the invention:

Figure 1 is an end elevation of one embodiment of the invention with the wiring circuit shown diagrammatically, A

Figure 2 is a side elevation of the embodiment of Figure 1, again showing the circuit diagrammatically,

Figure 3 is an end elevation showing a modification of the dancer roll and connections, and

Figure 4 is an end view showing another modification of the dancer roll and connections.

In Figures 1 and 2, the strand is shown proceeding from the supply means 2 about a dancer roll 3 through a traverse guide 4 onto the package 5 being wound upon core 6, driven by shaft 1, pulleys 8 and 9, connecting belt Ill, and the motor II, the shaft 12 of the motor ll being connected to the shaft l3 carrying pulley 9 by means of a worm and wheel (not shown). Illustratively, the supply means 2 may be a constant speed thread advancing device, such as a thread-advancing, thread-storing reel constituting the last one of a series in a machine for continuously spinning or for continuously processing artificial filaments or yarns. In addition, drying of the strand may have been performed by the supply.

reel. It is to be understood however that the invention is applicable to any form of strand proceeding from any equivalent supply means 2.

The winding machine shown may be of the type disclosed in U. S. Patent 801,941 to Wardwell, and has a traverse frame [4 which swings outwardly under the influence of the package as it increases in size, though the invention is not limited to this form of winding machine.

The dancer roll 3 is rotatably mounted upon the outer end of an arm l5 pivotally mounted at it. A stop pin 31 limits the downward motion of arm I5. A cam I1 is secured for rotation with the arm 15 about the pivot I6 and has a grooved periphery. A magnetic core I8 is suspended by Lil a flexible strand l9 secured to the cam I! at 20 and a spring 2| is similarly secured to the cam I! at 20 by means of a flexible strand 22. The core I8 is arranged to move within a guiding sleeve 23 extending within the reactance coil 24 which is connected in series with at least one winding of the A. C. motor II and with the supply lines 25 for A; C. current. A main switch 28 is provided to close the circuit for operating the motor. This switch is preferabl mounted on the cam l1 as shown. For convenience of mounting and a minimum operating force requirement, it may be of the tilting glass tube and mercury type. Switch 26 is arranged to open when the dancer roll arm l5 drops to the stop 31 and to close when the arm is raised from the stop. An auxiliary switch 21 is provided for starting from a standstill. This switch is provided with a spring 28 for opening it immediately upon release by the operator after the motor is started. The starting switch 21 is arranged to short-circuit the coil 24 and thus to provide full line voltage on the motor and consequently greater motor torque for starting. In operation the yarn is laced under the dancer roll before the winding operation is started. When the starting switch 21 is closed and winding commences, the yarn pulls upward on the dancer roll and closes switch 26. The operator then releases switch 21 which is returned to its open position by spring 28. The A. C. motor may be of any type having a variable speed characteristic, such as a series wound commutator type or a squirrel cage induction motor having a high resistance rotor. A direct current motor may be used if a rectifier 38 is inserted in the circuit as indicated by dotted lines in Figures 1 and 2.

Instead of a solid core 18, any other form may be used. For example a wound core supplied with electric current to form an electromagnetic core may be substituted for the solid core I8 of ma netic material, such as iron, cobalt, nickel or magnetic alloys, and it is to be understood that the term magnetic core is intended in its broad sense to include such equivalents. The wound core may be particularly desirable when winding light denier yarn because its smaller mass for a given reactive efiectiveness reduces the inertia of the dancer roll assembly and thereby reduces tension variations in the yarn. The coil and core constitute a pair of inductively related members.

As a package builds up during operation of the system, its increase of diameter causes a tendency for the yarn to increase in speed at the take up or winding position. This tendency causes the loop of yarn to lift dancer roll 3 which in turn allows the core I 8 to descend into the reactance coil 24. Such descent increases the reactance of the coil and thereby slows down the motor, thus reducing the speed of the package to the speed of yarn supply. The balancing position of the arm I progressively rises from the dotted line position |5a to the dotted line position l5b as the package buildsfrom an empty to a full condition respectively. It is to be noted that during the change from positions I5a to I51), the magnetic core I8 takes a gradually lower position. Since the pull of a solenoid upon a core increases from almost zero when the bottom of the core is above the top of the coil to a maximum and then decreases to zero when the magnetic centers coincide, the core I8 is preferably dimensioned and positioned with respect to coil 24 so that this lowering of the core (occurring during movement from I5a to I5b of the arm I5) is accompanied by an increase in the pull of the solenoid 24 upon the core and therefore b a gradual decrease in the tension upon the yarn in a manner which is generally desirable during package formation. Moreover, in the embodiments of Figures 1 and 2 the tension is further modified by the action of the spring 2| and the cam I1. As actually shown, the moment arm with which spring 2| acts through strand 22 gradually decreases as the package builds up. This decrease is preferably so adjusted as to more than compensate for the increase in tension imparted by the spring 2| as it elongates and thus to further progressively decrease the tension in the yarn during the winding of the package. An additional factor in decreasing yarn tension during package formationis the fact that as the pack-age builds up, the load upon the motor increases with a resultant increase in the electric current in the solenoid and, therefore, an increase in the pull of the solenoid upon the core. These several factors may take a different proportion of the burden in decreasing the yarn tension depending upon the particular system used in any particular embodiment. For example, an induction motor is very sensitive to load changes and consequently the greatest factor in reducing the yarn tension is the increase in current in the solenoid coil and in some cases this variation may be of such magnitude that the balancin position of the arm I5 may not rise to any substantial extent. On the other hand, when using a. series wound motor the main factor in reducing tension is the change in the balance position of the arm I5 which, by a suitable selection of the shape of cam l'l, may be accompanied with an additional either additive or partially substractive effect of the spring 2| associated with the cam I1.

In Figure 4, a modification is shown in which the tension is modified by the auxiliary counterweighted arm 29. As the package builds up, the moment of the counterweighted arm gradually decreases. which is additional to the tension decrease which is inherent in the device as shown in Figure 3 in which the arm I5 carries a counterweight I5. It will be noted that the angular relationship of the arm 29 may be adjusted as desired by virtue of the bolt 30 and the slot 3| of the rotatable hub plate from which arm I5 extends. Also the counterweight 32 is adjustable with respect to the arm 29. By virtue of these two adjustments, it 2; possible to obtain substantially constant tenion upon the strand being wound throughout the winding of the package and it is possible as well to obtain any desired constant rate of increase or decrease in the tension of the strand during the winding of the package. Preferably a gradual decrease in tension i used, in that a more satis- This produces a tension decrease factorily wound package is thus obtained. The rate of decrease may also be adjusted for the size of strand. Generally, heavier yarns need a greater rate of decrease in the tension.

Means may be provided for indicating when a package is full. As shown in Figures 1 and 2, a switch arm 33 is arranged in the path of a, projection 34 secured to the traverse frame l4. When the projection 34 strikes the switch 33, electric light 35 is turned on. The projection 34 is adjustably secured at 36 to the traverse frame so that any desired size of package may be obtained. If desired, the master switch 26 may be so arranged in the position occupied by the switch 33 that when projection 34 strikes the switch 26, it is opened and the mote: I I stops.

The present invention provides a simple arrangement for controlling the speed of a winding or take-up motor with a stepless variation and either with a constant tension in the strand being wound or a gradually increasing or decreasing tension in such strands as desired. The system involving the reactance coil and the magnetic core is extremely sensitive and consequently can be used reliabl and safely with the lightest weight yarn and strands. This is the result of the fact that no work except that required to overcome the inertia and friction of the dancer roll and core supporting system is needed to vary the speed of the motor. simple, reliable, adjustable and accurate control in the rate of decrease in tension during the winding of packages. In combination with a permanent condenser start induction motor and mercury switches, it provides an electrical type speed and tension control with no explosion hazard due to sparking and no corrosion hazard due to exposed contacts.

It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In combination, supply means for delivering a strand at substantially constant speed, take-up means for winding the strand into a package, an alternating current motor having a variable speed characteristic and having at least one exciting winding connected to an alternating current supply line for driving the take-up means, a reactance coil in series with said exciting winding of the motor and the current supply line, a pivotally mounted arm, a dancer roll rotatably mounted on the arm and suspended in a loop of the strand formed between the supply and takeup means, a magnetic core axially movable with respect to the coil, means connecting the core to the arm for movement simultaneously therewith and comprising a spring-controlled cam for gradually decreasing the tension in the strand at a predetermined rate throughout the winding of the package.

2. In combination, supply means for delivering a strand at substantially constant speed, take-up means for winding the strand into a package, an alternating current motor having a variable speed characteristic and having at least one exciting winding connected to an alternating current supply line for driving the take-up means, a reactance coil in series with said exciting winding of the motor and the current supply line, a pivotally mounted arm, a dancer roll rotatably mounted on the arm and suspended in a loop of the strand formed between the supply and takeup means, a magnetic core axially movable with It also provides for a.

respect to the coil and connected to the arm for movement simultaneously therewith, a counterweighted arm adjustably connected to the pivotallly mounted arm for controlling the variation of the tension in the strand in a predetermined manner throughout the winding of the package.

3. In combination, supply means for delivering a strand at substantially constant speed, take-up means for winding the strand into a package, an alternating current motor having a variable speed characteristic and having at least one exciting winding connected to an alternating current supply line for driving the take-up means, a reactance coil in series with said exciting winding of the motor and the current supply line, a pivotally mounted arm, a dancer roll rotatably mounted onthe arm and suspended in a loop of the strand formed between the supply and takeup means, a magnetic core axially movable with respect to the coil, a cam secured to the arm for pivotal motion therewith about a common axis, the core being suspended from a fixed point on the surface of the cam by flexible means connecting the core with the cam, and spring means secured to a fixed point of the cam so that it normally resists the gravitational efiect of the core tending to rotate the cam about its pivotal axis.

4. In combination, supply means for delivering a strand at substantially constant speed, take-up means for winding the strand into a package, an alternating current motor having a variable speed characteristic and having at least one exciting winding connected to an alternating current supply line for driving the take-up means, a reactance coil in series with said exciting winding of the motor and the current supply line, a pivotally mounted arm, a dancer roll rotatably mounted on the arm and suspended in a loop of the strand formed between the supply and takeup means, a magnetic core axially movable with respect to the coil, means connecting the core to the arm for movement simultaneously therewith and comprising a spring-controlled cam for gradually changing the tension in the strand at a predetermined rate throughout the winding of the package.

5. In combination, supply means for delivering a strand at substantially constant speed, take-up means for winding the strand into a package, an alternating current motor having a variable speed characteristic and having at least one exciting winding connected to an alternating current supply line for driving the take-up means, a reactance coil in series with said exciting winding of the motor and the current supply line, a pivotally mounted arm, a dancer roll rotatably mounted on the arm and suspended in a loop of the strand formed between the supply and takeup means, a magnetic core axially movable with respect to the coil and connected to the arm for movement simultaneously therewith, and counterweight means adjustably connected to the pivotally mounted arm for controlling the variation of the tension in the strand in a predetermined manner throughout the winding of the package.

6. In combination, means for continuously supplying a material of indefinite length, take-up means for winding the material into a package, an alternating current motor having a variable speed characteristic and having at least one exciting winding connected to an alternating current supply line for driving said take-up means whereby a change in speed of the motor is accompanied by a change in current through the winding, means for driving said supply means to deliver the material at substantially constant speed, a reactance coil in series with said exciting winding of the motor and the current supply line, a dancer roll in a loop of the material and pulling against the loop whereby it is movable by the material in response to any variation of the tension in the material resulting from any change of linear speed of material take-up, a magnetic core connected to the roll and movable axially with respect to the coil in respons to movements of the roll whereby a change of tension changes the positional relationship existing between the core and the coil and thereby changes the force exerted on the core by the coil, and mechanical means for superimposing an additional force, varying in respect to change of roll position, on the roll for providing a predetermined control of tension on the material throughout the take-up while maintaining a substantially constant speed of take-up.

7. In combination, means for continuously supplying a material of indefinite length, takeup means for winding the material into a package, an electric motor having a variable speed characteristic and having at least one exciting winding for driving said take-up means whereby a change in current through the winding is accompanied by a change in speed of the motor, a reactance coil in series with an alternating current supply line for controlling the current fed to the exciting winding of the motor, an element in a loop of the material and pulling against the loop whereby it is movable by the material in response to any variation of the tension in the material resulting from any change of linear speed of the material, a magnetic core connected to the element and movable axially with respect to the coil in response to movements of the element whereby a change of tension changes the positional relationship existing between the core and the coil thereby changing the reactance of the coil and the amount of current passing through the motor winding and the coil which thereby varies the speed of the motor and the force exerted on the core by the coil, and means for superimposing an additional force, varying in respect to change of element position, on the element for providing a predetermined control of tension on the material throughout the takeup and maintaining the take-up speed of the material substantially equal to the material supply speed.

8. A combination as defined in claim '1 pro vided with means for driving said supply means to deliver the material at substantially constant speed, said core having a position at the initiation of take-up in which the core center is axially displaced from the coil center and a position at the completion of take-up in which the core center is still axially displaced in the same direction from the coil center but at a lesser distance.

9. The combination of claim 7 in which the element is a dancer roll rotatably mounted on a pivotally mounted arm, and the core is connected to the arm and tends to turn it in a direction tending to decrease the pressure of the roll against the loop and the means for superimposing an additional force on the element comprises a counterweight connected to the arm and tend ing to increase the pressure of the roll against the loop.

10. The combination of claim 7 in which the element is a dancer roll rotatably mounted on a pivotally mounted arm, and the core is connected to the arm and tends to turn it in a direction tending to decrease the pressure of the roll against the loop and the means for superimposing an additional force on the element comprises a spring connected to the arm and tending to increase the pressure of the roll against the loop.

11. The combination of claim provided with a cam for connecting the spring to the arm to vary the moment arm of the spring in dependence on the extent of rotation of the arm, the core being suspended from the cam by a flexible strand.

12. In combination, means for continuously supplying a material of indefinite length, takeup means for winding the material into a package, an alternating current motor having a variable speed characteristic and having at least one exciting winding connected to an alternating current supply line for driving said take-up means whereby a change in current through the winding is accompanied by a change in speed of the motor, a reactance coil in series with the exciting winding of the motor and the current supply line, an element in a loop of the material and pulling against the loop whereby it is movable by the material in response to any variation of the tension in the material resulting from any change of linear speed of the material, a magnetic core connected to the element and movable axially with respect to the coil in response to movements of the element whereby a change of tension changes the positional relationship existing between the core and the coil thereby changing the reactance of the coil and the amount of current passing through the motor winding and the coil which thereby varies the speed of the motor and the force exerted on the core by the coil, and means for superimposing an 4 additional force, varying in respect to change of element position, on the element for providing a predetermined control of tension on the material throughout the take-up and maintaining the take-up speed of the material substantially equal to the material supply speed.

13. A combination as defined in claim 12 in which the element is a dancer roll and the means for superimposing an additional force on the element comprises a spring-controlled cam.

14. A combination as defined in claim 13 provided with means for driving said supply means to deliver the material at substantially constant speed, said core having a position at the initiation of take-up in which the core center is axially displaced from the coil center and a Position at the completion of take-up in which the core center is still axially displaced in the same direction from the coil center but at a lesser distance.

15. In combination, means for continuously supplying a material of indefinite length, take-up means for winding the material into a package, an alternating current motor having a variable speed characteristic and having at least one exciting winding connected to an alternating current supply line for driving said take-up means whereby a change in current through the winding is accompanied by a change in speed of the motor, means for driving said supply means to deliver the material at substantially constant speed, a reactance coil in series with said exciting winding of the motor and the current supply line, an element in a loop of the material and pulling against the loop whereby it is movable by the material in the element whereby a change of tension changes the positional relationship existing between the core and the coil thereby changing the reactance of the coil and the amount of current passing through the motor winding and the coil which thereby varies the speed of the motor and the force exerted on the core by the coil, said core and coil having a position at the initiation of take-up in which the core center is axially displaced from the coilcenter and a position at the completion of take-up in which the core center is still axially displaced in the same direction from the coil center but at a lesser distance, and mechanical means for superimposing a force on the element, varying in respect to change in position of the element, in addition to the force of reaction induced electrically between the core and the coil.

16. The combination of claim 15 in which the force superimposed by the mechanical means is opposed to the force induced electrically between the core and the coil.

17. The combination of claim 15 in which the element is a dancer roll rotatably mounted on a pivotally mounted arm, the core is connected to the arm and tends to turn it in a direction tending to decrease the pressure of the roll against the loop and the mechanical means comprises a spring connected to the arm and tending to increase the pressure of the roll against the loop.

18. The combination of claim 17 provided with a cam for connecting the. spring to the arm to vary the moment arm of the spring in dependence on the extent of rotation of the arm.

19. The combination of claim 18 in which the core is suspended from the cam by a flexible strand.

20. In combination, strand supply mean" takeup means for winding the strand into a package, a motor having a variable speed characteristic and having at least one exciting winding for driving said take-up means, means for driving said supply means, a reactance coil in series with an alternating current supply line for controlling the current fed to said exciting winding of the motor, an element in a loop of the strand movable in response to a variation of the tension in the strand, a magnetic core connected to the element and movable axially with respect to the coil in response to movement of the element, and means -for varying the tension exerted by the element in dependence upon the position of the element comprising a rotatable cam from which the core is suspended, an arm for supporting the element rotatably about the axis of rotation of the cam, and a spring for opposing rotation of the cam in one direction.

INGHAM S. ROBERTS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,304,565 Henderson May 27, 1919 1,706,164 Hull Mar. 19, 1929 1,832,430 Siebs Nov. 17, 1931 1,844,699 Stack Feb. 9, 1932 1,966,214 Palmer July 10, 1934 

